After a long pause, I decided to give distance fields a try. Here's result:

This is a CSG-based shape. Sphere minus torus minus cube. Positions of the primitives are hardcoded.

Here's the code:

DistanceFields.shader:

Shader "Unlit/RaycastDistanceFields"{
    Properties  {
        _MainTex ("Texture", 2D) = "white" {}
        _Color ("Color", Color) = (1, 1, 1 …